[Bug c/60090] For expression without ~, gcc -O1 emits "comparison of promoted ~unsigned with unsigned"

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60090

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |manu at gcc dot gnu.org

--- Comment #5 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #1)
> This (and a bunch of other related PRs) is about early folding in the FE.  
> c_fully_fold when optimize calls fold_build2 -> fold_binary_loc that
> transforms the expression and then we issue those seemingly unrelated
> warnings.  I'd say that while we want the exprs to be folded, we should
> issue diagnostics for the unfolded exprs.  (I think it's been discussed
> numerous times in the past.)
> 
> Nothing for stage4, but we/I should address this in gcc 5.0.

I think this should be the plan:

http://gcc.gnu.org/ml/gcc/2013-11/msg00253.html

but someone has to implement it ;-)

In those cases where folding helps to avoid false positives, it would be nice
to be able to still fold on-demand or to delay the warnings until folding can
happen.